Soldier's letters give first-hand look at Spanish flu pandemic

As World War I rages in Europe, fresh U.S. Army soldiers pass the time on a train ride to to Camp Forrest, Georgia. "The boys are just starting to sing," Martin Aloysius Culhane wrote on September 6, 1918, to his friend back home. "They've gotten back to 'Old Black Joe' so far."

Stephen Foster's classic song from the Civil War is about the death of slaves who had become his friends. But Culhane, known as "Al," and the soldiers who sang along could not know how much death would hunt the recruits on that train, most of whom never made it to Europe to fight in the Great War.

They would find themselves in the deadliest influenza pandemic in history.